There is a pipette for sampling an egg cell, a nucleus of the egg cell, or the like. A pipette 100 is generally operated by using a manipulator 130 as shown in FIG. 10.
The pipette 100 is attached to an attaching portion 132 extended from a fine motion unit 131 (the unit is capable of moving the attaching portion 132, to which the pipette is to be attached, horizontally and vertically at a 1 μm scale by a solenoid-operated system) of the manipulator 130. The pipette 100 is moved in any direction of x, y, and z according to a movement of the fine motion unit 131 based on instructions from the manipulator 130.
In addition, the pipette 100 includes a pump 120, and the pump 120 and the pipette 100 are connected with a tube 101.
As shown in FIG. 11, the pump 120 includes a cylinder 121 and a piston 122, and includes a stepping motor 123 for moving the piston 122 of the pump 120. The tube 101 for conveying a driving liquid is extended from the cylinder 121 of the pump 120 and a tip end of the tube 101 is connected to a longitudinal rear end of the pipette 100.
When the stepping motor 123 is rotated in accordance with instructions from the manipulator 130, a moving unit 125 connected to a driving shaft 124 of the stepping motor 123 is moved, so that the piston 122 is moved inside the cylinder 121. When the piston 122 is moved, the driving liquid inside the cylinder 121 is discharged from the cylinder 121 to the pipette 100 via the tube 101, or is sucked into the cylinder 121 from the pipette 100 via the tube 101.
With a use of the above-mentioned pipette 100, when the driving liquid is sucked by driving the pump 120 in accordance with instructions from the manipulator 130, the pipette 100 may suck a cell in a tip end of the pipette 100 or suck a sample inside the pipette 100. Conversely, when the driving liquid is discharged, the pipette 100 may discharge the sample inside the pipette 100 or discharge the cell, which has been sucked in the tip end of the pipette 100, from the tip end thereof.
There is, however, inconvenience in some operations performed by the manipulator 130.
One of the operations is transferring a plurality of cells in a Petri dish to another Petri dish.
In the case that this operation is performed by the above-mentioned manipulator 130, it is necessary to, first, place a Petri dish 140 containing cells to be transferred on a table 133, and then, move the table 133 upwardly to a position at which the cells can be manipulated by the pipette 100. After the cells are sucked into the tip end of the pipette 100 from the Petri dish 140, the table 133 is lowered. Thereafter, it is necessary to place a new Petri dish 140 on the table 133, and then, move the table 133 upwardly again to the position at which the cells can be manipulated by the pipette 100, and subsequently, discharge the cells from the tip end of the pipette 100 into the new Petri dish 140.
In view of the above, if the pipette 100 removed from the manipulator 130 can be manipulated by hand, an operation of sampling a sample by hand in conjunction with use of a microscope may be possible. Thus, there has been a demand from researchers for enabling such an operation.
In the case of the pipette 100 described above, however, every time the pipette 100 is moved, the tube 101 is largely bent and a volume of a space inside the tube 101 is changed. As a result, a suction force of the pipette 100 is changed. This change in suction force may cause discharge of the cells from the tip end of the pipette 100, or damage to the cells due to excessive suction. Consequently, it is not possible, in practice, to perform an operation of transferring cells between Petri dishes by hand.
In addition, when sampling a sample such as cells by hand using the above described pipette, a delicate manipulation and a delicate flow rate adjustment are required. However, the above described pipette 100 uses the stepping motor 123 as the pump 120, which leads to problems that a suction of a sample is performed in a stepwise manner by a certain amount, and thus, a so-called pulsating flow occurs and that a flow rate is high. If the pulsating flow occurs, excessive suction or insufficient suction of a sample may be caused, or conversely, excessive discharge or insufficient discharge of the sample may be caused. Also, if the flow rate is high, in the case of a small target sample (10 μm), it is impossible to hold the target sample in the tip end portion. Thus, it is impossible to sample a sample such as cells by hand using the pipette 100.